Herbs, Spices and Alcoholic Beverages May Elicit Cephalic Phase Responses, Involving Innate Reflexes, which Modulate Digestive Activity

Almost half of humanity suffers from digestive disorders so, it is not surprising that people have developed treatments with plants for these disorders.Today we have a wealth of information from all parts of the world and from many diverse cultures.What is common in this knowledge bank is the frequent occurrence of both bitter tasting and aromatic plants for digestive disorders.Bitter tasting plants are agonists of the TAS2R receptors and aromatic plants are agonists of several TRP somatosensory receptors.The prevailing view in physiology is oropharyngeal receptors act to regulate our food intake; to accept nutritionally rich substances, the sweet and umami tastes, and reject potentially toxic items, the bitter and sour tastes.In addition, we learn to consume and seek out the nutritionally rich substances and avoid potentially toxic items.Here is a discontinuity: traditional phytotherapy indicates the use of bitter tastants while physiology recommends avoidance.In addition, many popular vegetables taste bitter as do beer, coffee and tea.This paper proposes that both bitter tasting and aromatic plants elicit cephalic phase responses, involving innate reflexes, which modulate digestive activity.Furthermore, different bitter tasting plants produce characteristic responses that are not predictable from the single hedonic sensation of bitterness.Support for this proposal can be inferred from the available literature but goal-oriented research is required to substantiate or reject these concepts.• The somatosensory receptors in the nasopharyngeal and oropharyngeal cavities sense touch, pressure, position, movement, vibration, pain, temperature, pH and a wide range of both dietary and noxious compounds, referred to a as chemethesis.These receptors signal to the cognitive centres via the VI, IX and X cranial nerves [2]. Food SensingThe primary purpose of the three sensory systems is to determine the suitability of a food; should it be ingested or not, i.e. a binary decision.Smell is important even before a food enters the gustatory cavity.If something smells unpleasant then it is likely to be avoided, similarly if a smell is associated with nausea because of a previous exposure, it is likely to be avoided.On the other hand, pleasant smells, learned and unlearned, can be a powerful stimulant to human emotions [1].